Multiple droppers



March 3, 1970 c. J. sANDERsoN MULTIPLE DROPPERS Filed May 16, 1958Inventar [L v f /o/f/v SVA/)25.95001 JM ttorneys` U.S. Cl. 141--238 5Claims ABSTRACT F THE DISCLGSURE A multiple dropper for supplying equalmeasured drops of liquid simultaneously, comprises spaced droppersyringes, means actuating the plungers of all syringes in concert, ahydraulic ram for moving said actuating means and a cyclically operablefluid supply means for said ram, successive full cycles of operation ofsaid supply means moving said actuating means successively in the samedirection by predetermined equal amounts.

This invention relates to microtitre arrangements, used for serologicaltests and other purposes. In particular, the invention relates to amultiple dropper for delivering a number of accurately measured dropssimultaneously.

Microtitre plates, consisting of regularly arranged rows of cavities ina plastic plate, are used, diluent or reagent being added to each cavityfor comparative tests.

This addition has normally been made from a manually-operated calibratedpipette having a tip designed to give a measured drop of, for example,0.025 ml. The large number of cavities per plate make this verylaborious.

An object of the invention is to enable a measured drop of diluent,reagent or other liquid to be simultaneously supplied at each of aseries of positions, as, for ex ample, to each of a row of cavities on aTakatsky microtitre plate, thus providing a great saving of time with nosacrifice of accuracy.

A further object is to provide apparatus for this purpose which issimple, cheap to make, and reliable.

Accordingly, the invention comprises a multiple dropper having a seriesof spaced dropper syringes, actuating means for moving the plungers ofsaid syringes in concert a hydraulic ram for moving the actuating means,and a cyclically operable hydraulic uid supply means for said ram.

The supply means introduce a predetermined amount of uid into said ramon each full cycle of operation. The supply means is conveniently andadjustable-delivery automatic syringe.

Preferably a hydraulic fiuid reservoir is provided from which saidsupply means draws fluid and into which the fluid from said ram emptieson resetting of the apparatus.

ln order that the invention may be better understood, an exemplaryembodiment for use with a microtitre plate will be described, withreference to the accompanying drawing, which shows a front elevation.

The apparatus includes a fiat base-plate having spaced vertical rods 11,12 extending from it. A top cross-piece 13 between the rods supports aLuer-lok 2O ml. glass syringe barrel 14, the flange 15 of the syringe 14being fixed to the cross-piece and the plunger 16 ex' tending downwards.Middle and lower cross-pieces 17, 18 hold the barrels 19 of twelve 1 ml.syringes, arranged side by side with their tips 81 mm. apart (thespacing between cavities of a microtitre plate). Each tip is calibratedto give a preselected drop size (eg. 0.025 mL). The plungers 29 of the 1ml. syringes extend upwards and United States Patent O- ice are fixed toa movable cross-piece 21 sliding on the rods 11, 12. The plunger 16 ofthe 20 ml. syringe is fixed to the upper side of the movable cross-piece21. The movable cross-piece is supported on a light helical spring 22round each rod to prevent its weight pressing the 1 ml. syringe plungersdown.

The actuating means (cross-piece 21) for moving plungers 20 in concertis therefore moved by the 20 ml. syringe 14, 16 held at the top of theframework and acting as a hydraulic ram. The head of the plunger 16rests on the sliding cross-piece 21. Forcing water into the 20 ml.syringe will force the plunger 16 and hence the sliding cross-piece 21down, expelling fluid from the dropper syringes 19, 20. The 20 ml. and 1ml. syringes have the same length of action so that the 1 ml. syringes19, 20 can be completely filled and emptied with the full stroke of the20 ml. syringe 14, 16. Hydraulic fluid supply for the 20 ml. syringe 14,16 is by an automatic syringe 23 fitted with the normal three-way valve23A. The inlet tube 24 is immersed in a reservoir of water 25.Depressing the plunger of syringe 23 forces water up a pressure line 26connected to the syringe outlet and into the 20 ml. syringe 14, 16 bymeans of another three-way valve 27, forcing the plunger 16 down a smalldistance.

The outlet of the three-way valve 27 is fitted with a stopcock 28 andconnected by return line 29 to the reservoir 25. Lifting the slidingcross-piece with the stopcock open returns the water in the barrel 14 tothe reservoir 25 and lifts the plungers of the syringes 19, 20.

On the base plate 10 are fitted guides 30 to guide the microtitre plate31. The base-plate 10 can preferably be lowered so that the diluentcontainer can be placed under the dropper tips to fill the droppersyringes, although this is not shown. In its upper position the baseplate 10 holds the microtitre plate 31 just a short distance below thedropper tips. The microtitre plates are moved into position under thedropper with one hand and the automatic syringe is operated with theother.

The perspex diluent containers (not shown) are made to allow the droppertips to reach the bottom, ensuring no wastage of diluent when thedropper syringes 19, 20 are filled. The reagent cells are perspex blockscontaining at least one row of twelve 2 ml. cavities spaced so that onedropper tip ts into each cavity. This allows each syringe 19, 20 to befilled with a different reagent.

The apparatus is operated as follows:

The syringes 19, 20 are filled by immersing their tips in the diluent orreagent containers and pushing the sliding cross-piece 21 upwards fromits lowermost position with the stopcock 27 open.

With the stopcock 27 still open, repeated operation of the automaticsyringe 23 will remove any air bubbles from the hydraulic system.

Stopcock 27 is then closed and the system is adjusted to give one dropat each syringe 19, 20 for each full depression of the plunger of theautomatic syringe 23 by adjusting the automatic syringe delivery amountover some ten drops and locking it at the proper setting. Since thestrokes of syringes 14, 16 and 19, 20 are equal and their volume ratiois 20: 1, the volume supplied by syringe 23 will be nearly twenty timesthe amount delivered from syringe 19, 20.

The -microtitre plate 31 is then positioned by the guide 30 on the baseplate 10 and drops placed in the cavities of each row by one fulldepression of the syringe 23, as each row is positioned under the tipsof syringes 19, 20.

It will be seen that the whole contents of each syringe 19, 20 isdelivered in successive desired amounts. Each full operation of syringe23 moves crossbar 21 downwards only, so that many deliveries areobtained between refillings of syringes 19, 20.

With the very small amounts delivered (eg. 0.025 ml.) such operation isessential. Any operation attempting to charge a syringe 19, 20 betweendelivery of successive drops is unworkable.

In the example illustrated, full use is made of standard componentsnormally available in the laboratory so that the equipment is simple andcheap to construct.

It will however, be understood that various changes and modificationsmay be made in the arrangement described.

I claim: 1. A multiple dropper including a series of space droppersyringes; actuating means for moving the plungers of said syringes inconcert; a hydraulic ram for moving said actuating means; a hydraulicfluid supply means for said ram, characterized in that said sup,- plymeans is operable cyclically and, on successive full cycles of operationthereof, produces successive predetermined equal movements of saidactuating 4means in a direction to express drops from said droppersyringes.

2. A multiple dropper as claimed in claim 1, inwhich the dropper syringebarrels are fixed in a cross-bar of a vertical frame, and said actuatingmeans includes a second cross-bar slidable on said frame to which saidplungers are attached, and said ram comprises an inverted syringe withits barrel xed on a third cross-bar, the stroke of said inverted syringeand each said dropper syringes being equal, but the capacity of saidinverted syringe being greater than that of a dropper syringe.

3. A multiple dropper as claimed in claim 2, in which said supply meansincludes an adjustable delivery automatic syringe connected by athree-Way valve to a hydraulic fluid reservoir and to said ram.

4. A multiple dropper as claimed in claim 3, in which the barrel of saidinverted syringe is connected via a three-Way valve to said automaticsyringe and to a return line leading to said reservoir, said return linehaving a stopcock therein.

5. A multiple dropper as claimed in claim 1, including avertically-adjustable horizontal base-plate beneath the delivery pointsof said dropper syringes, said base-plate being provided with guides forguiding a plate of liquidcontaining cells beneath the dropper syringes.

References Cited UNITED STATES PATENTS 2,932,330 4/1960 Donofrio 141-238X 3,311,271 3/1967 Middleton 222-334 X FOREIGN PATENTS 1,413,152 4/1965France.

ROBERT B. REEVES, Primary Examiner H. S. LANE, Assistant Examiner U.S.C1. X.R.

